Throughout Secret Societies, Gardiner uncovers an ancient secret society thought to have died out many years ago and gets to the core of the secret societies' belief systems. He explores the secret origins of Freemasonry and the links to secret Serpent Cults, Investigates the secret hidden meaning of King Arthur and Robin Hood and examines the claimants to the name of Illuminati, and analyzes the history of the group in Europe and America. Gardiner reveals the secret links within the Vatican and the Nazi Party and looks in-depth at the white-powdered gold theory supposedly kept secret by orders throughout time and radically re-appraises it. He also shows the link between the so-called enlightenment experience and the control of our minds.

Nobody in the genre involves themselves in the tale in the same way that Gardiner does, and here he shows that the search for ultimate truth can often be a terrifying one.